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<p><strong>&#x5BF9;&#x8C61;</strong>&#xFF08;object&#xFF09;&#x662F; JavaScript &#x8BED;&#x8A00;&#x7684;&#x6838;&#x5FC3;&#x6982;&#x5FF5;&#xFF0C;&#x4E5F;&#x662F;&#x6700;&#x91CD;&#x8981;&#x7684;&#x6570;&#x636E;&#x7C7B;&#x578B;&#x3002;</p>
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<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {
  foo: <span class="hljs-string">&apos;Hello&apos;</span>,
  bar: <span class="hljs-string">&apos;World&apos;</span>
};
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5927;&#x62EC;&#x53F7;&#x5C31;&#x5B9A;&#x4E49;&#x4E86;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#xFF0C;&#x5B83;&#x88AB;&#x8D4B;&#x503C;&#x7ED9;&#x53D8;&#x91CF;<code>obj</code>&#xFF0C;&#x6240;&#x4EE5;&#x53D8;&#x91CF;<code>obj</code>&#x5C31;&#x6307;&#x5411;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x3002;&#x8BE5;&#x5BF9;&#x8C61;&#x5185;&#x90E8;&#x5305;&#x542B;&#x4E24;&#x4E2A;&#x952E;&#x503C;&#x5BF9;&#xFF08;&#x53C8;&#x79F0;&#x4E3A;&#x4E24;&#x4E2A;&#x201C;&#x6210;&#x5458;&#x201D;&#xFF09;&#xFF0C;&#x7B2C;&#x4E00;&#x4E2A;&#x952E;&#x503C;&#x5BF9;&#x662F;<code>foo: &apos;Hello&apos;</code>&#xFF0C;&#x5176;&#x4E2D;<code>foo</code>&#x662F;&#x201C;&#x952E;&#x540D;&#x201D;&#xFF08;&#x6210;&#x5458;&#x7684;&#x540D;&#x79F0;&#xFF09;&#xFF0C;&#x5B57;&#x7B26;&#x4E32;<code>Hello</code>&#x662F;&#x201C;&#x952E;&#x503C;&#x201D;&#xFF08;&#x6210;&#x5458;&#x7684;&#x503C;&#xFF09;&#x3002;&#x952E;&#x540D;&#x4E0E;&#x952E;&#x503C;&#x4E4B;&#x95F4;&#x7528;&#x5192;&#x53F7;&#x5206;&#x9694;&#x3002;&#x7B2C;&#x4E8C;&#x4E2A;&#x952E;&#x503C;&#x5BF9;&#x662F;<code>bar: &apos;World&apos;</code>&#xFF0C;<code>bar</code>&#x662F;&#x952E;&#x540D;&#xFF0C;<code>World</code>&#x662F;&#x952E;&#x503C;&#x3002;&#x4E24;&#x4E2A;&#x952E;&#x503C;&#x5BF9;&#x4E4B;&#x95F4;&#x7528;&#x9017;&#x53F7;&#x5206;&#x9694;&#x3002;</p>
<p><strong><em>ES5 &#x91CA;&#x4E49;:</em></strong></p>
<p>JavaScript &#x539F;&#x751F;&#x63D0;&#x4F9B;<code>Object</code>&#x5BF9;&#x8C61;&#xFF08;&#x6CE8;&#x610F;&#x8D77;&#x9996;&#x7684;<code>O</code>&#x662F;&#x5927;&#x5199;&#xFF09;&#xFF0C;&#x672C;&#x7AE0;&#x4ECB;&#x7ECD;&#x8BE5;&#x5BF9;&#x8C61;&#x539F;&#x751F;&#x7684;&#x5404;&#x79CD;&#x65B9;&#x6CD5;&#x3002;</p>
<p>JavaScript &#x7684;&#x6240;&#x6709;&#x5176;&#x4ED6;&#x5BF9;&#x8C61;&#x90FD;&#x7EE7;&#x627F;&#x81EA;<code>Object</code>&#x5BF9;&#x8C61;&#xFF0C;&#x5373;&#x90A3;&#x4E9B;&#x5BF9;&#x8C61;&#x90FD;&#x662F;<code>Object</code>&#x7684;&#x5B9E;&#x4F8B;&#x3002;</p>
<p><code>Object</code>&#x5BF9;&#x8C61;&#x7684;&#x539F;&#x751F;&#x65B9;&#x6CD5;&#x5206;&#x6210;&#x4E24;&#x7C7B;&#xFF1A;<code>Object</code>&#x672C;&#x8EAB;&#x7684;&#x65B9;&#x6CD5;&#x4E0E;<code>Object</code>&#x7684;&#x5B9E;&#x4F8B;&#x65B9;&#x6CD5;&#x3002;</p>
<p>&#x533A;&#x522B;&#x7684;&#x8BDD;&#xFF1A;&#x5B9E;&#x4F8B;&#x65B9;&#x6CD5;&#x662F;&#x88AB;&#x7EE7;&#x627F;&#x7684;&#x65B9;&#x6CD5;&#xFF0C;&#x672C;&#x8EAB;&#x65B9;&#x6CD5;&#x662F;&#x901A;&#x8FC7;Object&#x8C03;&#x7528;&#x3002;</p>
<ul>
<li><code>Object</code><strong><em>&#x5BF9;&#x8C61;&#x672C;&#x8EAB;&#x7684;&#x65B9;&#x6CD5;</em></strong>&#xFF1A;</li>
</ul>
<pre><code class="lang-js"><span class="hljs-built_in">Object</span>.print = <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{
  <span class="hljs-built_in">console</span>.log(<span class="hljs-string">&apos;hello world&apos;</span>);
};
<span class="hljs-built_in">Object</span>.print();

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Terminal</span>  =<span class="hljs-string">====</span>&gt;</span>
hello world
</span></code></pre>
<ul>
<li><code>Object</code><strong><em>&#x5B9E;&#x4F8B;&#x65B9;&#x6CD5;</em></strong>&#xFF1A;</li>
</ul>
<pre><code class="lang-js"><span class="hljs-built_in">Object</span>.prototype.print = <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{
  <span class="hljs-built_in">console</span>.log(<span class="hljs-string">&apos;prototype: hello world&apos;</span>);
};
<span class="hljs-keyword">var</span> object = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Object</span>();
object.print();

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Terminal</span>  =<span class="hljs-string">====</span>&gt;</span>
prototype: hello world
</span></code></pre>
<p><strong><em>Object()</em></strong></p>
<p><code>Object</code>&#x672C;&#x8EAB;&#x662F;&#x4E00;&#x4E2A;&#x51FD;&#x6570;&#xFF0C;&#x53EF;&#x4EE5;&#x5F53;&#x4F5C;&#x5DE5;&#x5177;&#x65B9;&#x6CD5;&#x4F7F;&#x7528;&#xFF0C;&#x5C06;&#x4EFB;&#x610F;&#x503C;&#x8F6C;&#x4E3A;&#x5BF9;&#x8C61;&#x3002;&#x8FD9;&#x4E2A;&#x65B9;&#x6CD5;&#x5E38;&#x7528;&#x4E8E;&#x4FDD;&#x8BC1;&#x67D0;&#x4E2A;&#x503C;&#x4E00;&#x5B9A;&#x662F;&#x5BF9;&#x8C61;&#x3002;</p>
<p>&#x5982;&#x679C;&#x53C2;&#x6570;&#x4E3A;&#x7A7A;&#xFF08;&#x6216;&#x8005;&#x4E3A;<code>undefined</code>&#x548C;<code>null</code>&#xFF09;&#xFF0C;<code>Object()</code>&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x7A7A;&#x5BF9;&#x8C61;&#x3002;</p>
<pre><code class="lang-JS"><span class="hljs-keyword">var</span> obj = <span class="hljs-built_in">Object</span>();
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
<span class="hljs-keyword">var</span> obj = <span class="hljs-built_in">Object</span>(<span class="hljs-literal">undefined</span>);
<span class="hljs-keyword">var</span> obj = <span class="hljs-built_in">Object</span>(<span class="hljs-literal">null</span>);

obj <span class="hljs-keyword">instanceof</span> <span class="hljs-built_in">Object</span> <span class="hljs-comment">// true</span>
</code></pre>
<h3 id="&#x952E;&#x540D;">&#x952E;&#x540D;</h3>
<p>&#x5BF9;&#x8C61;&#x7684;&#x6240;&#x6709;&#x952E;&#x540D;&#x90FD;&#x662F;&#x5B57;&#x7B26;&#x4E32;&#xFF08;ES6 &#x53C8;&#x5F15;&#x5165;&#x4E86; Symbol &#x503C;&#x4E5F;&#x53EF;&#x4EE5;&#x4F5C;&#x4E3A;&#x952E;&#x540D;&#xFF09;&#xFF0C;&#x6240;&#x4EE5;&#x52A0;&#x4E0D;&#x52A0;&#x5F15;&#x53F7;&#x90FD;&#x53EF;&#x4EE5;&#x3002;&#x4E0A;&#x9762;&#x7684;&#x4EE3;&#x7801;&#x4E5F;&#x53EF;&#x4EE5;&#x5199;&#x6210;&#x4E0B;&#x9762;&#x8FD9;&#x6837;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {
  <span class="hljs-string">&apos;foo&apos;</span>: <span class="hljs-string">&apos;Hello&apos;</span>,
  <span class="hljs-string">&apos;bar&apos;</span>: <span class="hljs-string">&apos;World&apos;</span>
};
</code></pre>
<p>&#x5982;&#x679C;&#x952E;&#x540D;&#x662F;&#x6570;&#x503C;&#xFF0C;&#x4F1A;&#x88AB;&#x81EA;&#x52A8;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;&#x3002;</p>
<p>&#x5982;&#x679C;&#x952E;&#x540D;&#x4E0D;&#x7B26;&#x5408;&#x6807;&#x8BC6;&#x540D;&#x7684;&#x6761;&#x4EF6;&#xFF08;&#x6BD4;&#x5982;&#x7B2C;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E3A;&#x6570;&#x5B57;&#xFF0C;&#x6216;&#x8005;&#x542B;&#x6709;&#x7A7A;&#x683C;&#x6216;&#x8FD0;&#x7B97;&#x7B26;&#xFF09;&#xFF0C;&#x4E14;&#x4E5F;&#x4E0D;&#x662F;&#x6570;&#x5B57;&#xFF0C;&#x5219;&#x5FC5;&#x987B;&#x52A0;&#x4E0A;&#x5F15;&#x53F7;&#xFF0C;&#x5426;&#x5219;&#x4F1A;&#x62A5;&#x9519;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-comment">// &#x62A5;&#x9519;</span>
<span class="hljs-keyword">var</span> obj = {
  <span class="hljs-number">1</span>p: <span class="hljs-string">&apos;Hello World&apos;</span>
};

<span class="hljs-comment">// &#x4E0D;&#x62A5;&#x9519;</span>
<span class="hljs-keyword">var</span> obj = {
  <span class="hljs-string">&apos;1p&apos;</span>: <span class="hljs-string">&apos;Hello World&apos;</span>,
  <span class="hljs-string">&apos;h w&apos;</span>: <span class="hljs-string">&apos;Hello World&apos;</span>,
  <span class="hljs-string">&apos;p+q&apos;</span>: <span class="hljs-string">&apos;Hello World&apos;</span>
};
</code></pre>
<p>&#x4E0A;&#x9762;&#x5BF9;&#x8C61;&#x7684;&#x4E09;&#x4E2A;&#x952E;&#x540D;&#xFF0C;&#x90FD;&#x4E0D;&#x7B26;&#x5408;&#x6807;&#x8BC6;&#x540D;&#x7684;&#x6761;&#x4EF6;&#xFF0C;&#x6240;&#x4EE5;&#x5FC5;&#x987B;&#x52A0;&#x4E0A;&#x5F15;&#x53F7;&#x3002;</p>
<h3 id="&#x5BF9;&#x8C61;&#x7684;&#x5F15;&#x7528;">&#x5BF9;&#x8C61;&#x7684;&#x5F15;&#x7528;</h3>
<p>&#x5982;&#x679C;&#x4E0D;&#x540C;&#x7684;&#x53D8;&#x91CF;&#x540D;&#x6307;&#x5411;&#x540C;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#xFF0C;&#x90A3;&#x4E48;&#x5B83;&#x4EEC;&#x90FD;&#x662F;&#x8FD9;&#x4E2A;&#x5BF9;&#x8C61;&#x7684;&#x5F15;&#x7528;&#xFF0C;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#x6307;&#x5411;&#x540C;&#x4E00;&#x4E2A;&#x5185;&#x5B58;&#x5730;&#x5740;&#x3002;&#x4FEE;&#x6539;&#x5176;&#x4E2D;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#xFF0C;&#x4F1A;&#x5F71;&#x54CD;&#x5230;&#x5176;&#x4ED6;&#x6240;&#x6709;&#x53D8;&#x91CF;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> o1 = {};
<span class="hljs-keyword">var</span> o2 = o1;

o1.a = <span class="hljs-number">1</span>;
o2.a <span class="hljs-comment">// 1</span>

o2.b = <span class="hljs-number">2</span>;
o1.b <span class="hljs-comment">// 2</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>o1</code>&#x548C;<code>o2</code>&#x6307;&#x5411;&#x540C;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#xFF0C;&#x56E0;&#x6B64;&#x4E3A;&#x5176;&#x4E2D;&#x4EFB;&#x4F55;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#x6DFB;&#x52A0;&#x5C5E;&#x6027;&#xFF0C;&#x53E6;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#x90FD;&#x53EF;&#x4EE5;&#x8BFB;&#x5199;&#x8BE5;&#x5C5E;&#x6027;&#x3002;</p>
<p>&#x6B64;&#x65F6;&#xFF0C;&#x5982;&#x679C;&#x53D6;&#x6D88;&#x67D0;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#x5BF9;&#x4E8E;&#x539F;&#x5BF9;&#x8C61;&#x7684;&#x5F15;&#x7528;&#xFF0C;&#x4E0D;&#x4F1A;&#x5F71;&#x54CD;&#x5230;&#x53E6;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> o1 = {};
<span class="hljs-keyword">var</span> o2 = o1;

o1 = <span class="hljs-number">1</span>;
o2 <span class="hljs-comment">// {}</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>o1</code>&#x548C;<code>o2</code>&#x6307;&#x5411;&#x540C;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#xFF0C;&#x7136;&#x540E;<code>o1</code>&#x7684;&#x503C;&#x53D8;&#x4E3A;1&#xFF0C;&#x8FD9;&#x65F6;&#x4E0D;&#x4F1A;&#x5BF9;<code>o2</code>&#x4EA7;&#x751F;&#x5F71;&#x54CD;&#xFF0C;<code>o2</code>&#x8FD8;&#x662F;&#x6307;&#x5411;&#x539F;&#x6765;&#x7684;&#x90A3;&#x4E2A;&#x5BF9;&#x8C61;&#x3002;</p>
<p>&#x4F46;&#x662F;&#xFF0C;&#x8FD9;&#x79CD;&#x5F15;&#x7528;&#x53EA;&#x5C40;&#x9650;&#x4E8E;&#x5BF9;&#x8C61;&#xFF0C;&#x5982;&#x679C;&#x4E24;&#x4E2A;&#x53D8;&#x91CF;&#x6307;&#x5411;&#x540C;&#x4E00;&#x4E2A;&#x539F;&#x59CB;&#x7C7B;&#x578B;&#x7684;&#x503C;&#x3002;&#x90A3;&#x4E48;&#xFF0C;&#x53D8;&#x91CF;&#x8FD9;&#x65F6;&#x90FD;&#x662F;&#x503C;&#x7684;&#x62F7;&#x8D1D;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> x = <span class="hljs-number">1</span>;
<span class="hljs-keyword">var</span> y = x;

x = <span class="hljs-number">2</span>;
y <span class="hljs-comment">// 1</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x7684;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5F53;<code>x</code>&#x7684;&#x503C;&#x53D1;&#x751F;&#x53D8;&#x5316;&#x540E;&#xFF0C;<code>y</code>&#x7684;&#x503C;&#x5E76;&#x4E0D;&#x53D8;&#xFF0C;&#x8FD9;&#x5C31;&#x8868;&#x793A;<code>y</code>&#x548C;<code>x</code>&#x5E76;&#x4E0D;&#x662F;&#x6307;&#x5411;&#x540C;&#x4E00;&#x4E2A;&#x5185;&#x5B58;&#x5730;&#x5740;&#x3002;</p>
<h2 id="&#x5C5E;&#x6027;&#x7684;&#x64CD;&#x4F5C;">&#x5C5E;&#x6027;&#x7684;&#x64CD;&#x4F5C;</h2>
<h3 id="&#x5C5E;&#x6027;&#x7684;&#x8BFB;&#x53D6;">&#x5C5E;&#x6027;&#x7684;&#x8BFB;&#x53D6;</h3>
<p>&#x8BFB;&#x53D6;&#x5BF9;&#x8C61;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x6709;&#x4E24;&#x79CD;&#x65B9;&#x6CD5;&#xFF0C;&#x4E00;&#x79CD;&#x662F;&#x4F7F;&#x7528;&#x70B9;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x8FD8;&#x6709;&#x4E00;&#x79CD;&#x662F;&#x4F7F;&#x7528;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {
  p: <span class="hljs-string">&apos;Hello World&apos;</span>
};

obj.p <span class="hljs-comment">// &quot;Hello World&quot;</span>
obj[<span class="hljs-string">&apos;p&apos;</span>] <span class="hljs-comment">// &quot;Hello World&quot;</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x5206;&#x522B;&#x91C7;&#x7528;&#x70B9;&#x8FD0;&#x7B97;&#x7B26;&#x548C;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x8BFB;&#x53D6;&#x5C5E;&#x6027;<code>p</code>&#x3002;</p>
<p>&#x8BF7;&#x6CE8;&#x610F;&#xFF0C;&#x5982;&#x679C;&#x4F7F;&#x7528;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x952E;&#x540D;&#x5FC5;&#x987B;&#x653E;&#x5728;&#x5F15;&#x53F7;&#x91CC;&#x9762;&#xFF0C;&#x5426;&#x5219;&#x4F1A;&#x88AB;&#x5F53;&#x4F5C;&#x53D8;&#x91CF;&#x5904;&#x7406;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> foo = <span class="hljs-string">&apos;bar&apos;</span>;

<span class="hljs-keyword">var</span> obj = {
  foo: <span class="hljs-number">1</span>,
  bar: <span class="hljs-number">2</span>
};

obj.foo  <span class="hljs-comment">// 1</span>
obj[foo]  <span class="hljs-comment">// 2</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5F15;&#x7528;&#x5BF9;&#x8C61;<code>obj</code>&#x7684;<code>foo</code>&#x5C5E;&#x6027;&#x65F6;&#xFF0C;&#x5982;&#x679C;&#x4F7F;&#x7528;&#x70B9;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;<code>foo</code>&#x5C31;&#x662F;&#x5B57;&#x7B26;&#x4E32;&#xFF1B;&#x5982;&#x679C;&#x4F7F;&#x7528;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x4F46;&#x662F;&#x4E0D;&#x4F7F;&#x7528;&#x5F15;&#x53F7;&#xFF0C;&#x90A3;&#x4E48;<code>foo</code>&#x5C31;&#x662F;&#x4E00;&#x4E2A;&#x53D8;&#x91CF;&#xFF0C;&#x6307;&#x5411;&#x5B57;&#x7B26;&#x4E32;<code>bar</code>&#x3002;</p>
<p>&#x6570;&#x5B57;&#x952E;&#x53EF;&#x4EE5;&#x4E0D;&#x52A0;&#x5F15;&#x53F7;&#xFF0C;&#x56E0;&#x4E3A;&#x4F1A;&#x81EA;&#x52A8;&#x8F6C;&#x6210;&#x5B57;&#x7B26;&#x4E32;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {
  <span class="hljs-number">0.7</span>: <span class="hljs-string">&apos;Hello World&apos;</span>
};

obj[<span class="hljs-string">&apos;0.7&apos;</span>] <span class="hljs-comment">// &quot;Hello World&quot;</span>
obj[<span class="hljs-number">0.7</span>] <span class="hljs-comment">// &quot;Hello World&quot;</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5BF9;&#x8C61;<code>obj</code>&#x7684;&#x6570;&#x5B57;&#x952E;<code>0.7</code>&#xFF0C;&#x52A0;&#x4E0D;&#x52A0;&#x5F15;&#x53F7;&#x90FD;&#x53EF;&#x4EE5;&#xFF0C;&#x56E0;&#x4E3A;&#x4F1A;&#x88AB;&#x81EA;&#x52A8;&#x8F6C;&#x4E3A;&#x5B57;&#x7B26;&#x4E32;&#x3002;</p>
<p>&#x6CE8;&#x610F;&#xFF0C;&#x6570;&#x503C;&#x952E;&#x540D;&#x4E0D;&#x80FD;&#x4F7F;&#x7528;&#x70B9;&#x8FD0;&#x7B97;&#x7B26;&#xFF08;&#x56E0;&#x4E3A;&#x4F1A;&#x88AB;&#x5F53;&#x6210;&#x5C0F;&#x6570;&#x70B9;&#xFF09;&#xFF0C;&#x53EA;&#x80FD;&#x4F7F;&#x7528;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {
  <span class="hljs-number">123</span>: <span class="hljs-string">&apos;hello world&apos;</span>
};

obj<span class="hljs-number">.123</span> <span class="hljs-comment">// &#x62A5;&#x9519;</span>
obj[<span class="hljs-number">123</span>] <span class="hljs-comment">// &quot;hello world&quot;</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x8868;&#x8FBE;&#x5F0F;&#xFF0C;&#x5BF9;&#x6570;&#x503C;&#x952E;&#x540D;<code>123</code>&#x4F7F;&#x7528;&#x70B9;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x7ED3;&#x679C;&#x62A5;&#x9519;&#x3002;&#x7B2C;&#x4E8C;&#x4E2A;&#x8868;&#x8FBE;&#x5F0F;&#x4F7F;&#x7528;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x7ED3;&#x679C;&#x5C31;&#x662F;&#x6B63;&#x786E;&#x7684;&#x3002;</p>
<h3 id="&#x5C5E;&#x6027;&#x7684;&#x8D4B;&#x503C;">&#x5C5E;&#x6027;&#x7684;&#x8D4B;&#x503C;</h3>
<p>&#x70B9;&#x8FD0;&#x7B97;&#x7B26;&#x548C;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x4E0D;&#x4EC5;&#x53EF;&#x4EE5;&#x7528;&#x6765;&#x8BFB;&#x53D6;&#x503C;&#xFF0C;&#x8FD8;&#x53EF;&#x4EE5;&#x7528;&#x6765;&#x8D4B;&#x503C;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {};

obj.foo = <span class="hljs-string">&apos;Hello&apos;</span>;
obj[<span class="hljs-string">&apos;bar&apos;</span>] = <span class="hljs-string">&apos;World&apos;</span>;
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5206;&#x522B;&#x4F7F;&#x7528;&#x70B9;&#x8FD0;&#x7B97;&#x7B26;&#x548C;&#x65B9;&#x62EC;&#x53F7;&#x8FD0;&#x7B97;&#x7B26;&#xFF0C;&#x5BF9;&#x5C5E;&#x6027;&#x8D4B;&#x503C;&#x3002;</p>
<p>JavaScript &#x5141;&#x8BB8;&#x5C5E;&#x6027;&#x7684;&#x201C;&#x540E;&#x7ED1;&#x5B9A;&#x201D;&#xFF0C;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;&#x4F60;&#x53EF;&#x4EE5;&#x5728;&#x4EFB;&#x610F;&#x65F6;&#x523B;&#x65B0;&#x589E;&#x5C5E;&#x6027;&#xFF0C;&#x6CA1;&#x5FC5;&#x8981;&#x5728;&#x5B9A;&#x4E49;&#x5BF9;&#x8C61;&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x5C31;&#x5B9A;&#x4E49;&#x597D;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = { p: <span class="hljs-number">1</span> };

<span class="hljs-comment">// &#x7B49;&#x4EF7;&#x4E8E;</span>

<span class="hljs-keyword">var</span> obj = {};
obj.p = <span class="hljs-number">1</span>;
</code></pre>
<h4 id="get-set"><strong><em>get() set():</em></strong></h4>
<pre><code class="lang-js"><span class="hljs-keyword">const</span> object = {
  $n: <span class="hljs-number">5</span>,
  get next() {
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">this</span>.$n++;
  },
  set next(value) {
    <span class="hljs-keyword">this</span>.$n &lt; value ? <span class="hljs-keyword">this</span>.$n = value:
    <span class="hljs-built_in">console</span>.log(<span class="hljs-string">&apos;the new value must bigger than before&apos;</span>);
  },
};

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Test</span>  =<span class="hljs-string">====</span>&gt;</span>
let n = object.next;
assert.strictEqual(n, 5);
object.next = 10;
n = object.next;
assert.strictEqual(n, 10);
object.next = 5;
n = object.next;
assert.strictEqual(n, 11);

<span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Teiminal</span>  =<span class="hljs-string">====</span>&gt;</span>
/* &#x6D4B;&#x8BD5;&#x901A;&#x8FC7; */
the new value must bigger than before
</span></code></pre>
<p>&#x4E0A;&#x9762;&#x7684;&#x4F8B;&#x5B50;&#x662F; &#x901A;&#x8FC7; <code>next</code> &#x6765;&#x8D4B;&#x503C;&#xFF0C;&#x4F46;&#x662F;&#x6BD4; <code>$n</code> &#x5C0F;&#x7684;&#x503C;&#x4E0D;&#x80FD;&#x901A;&#x8FC7;<code>set()</code> &#x51FD;&#x6570;&#x8D4B;&#x4E88;&#x3002;&#x56E0;&#x6B64;&#x7B2C;&#x4E00;&#x6B21; <code>next = 10</code>,&#x6CA1;&#x6709;&#x95EE;&#x9898;&#xFF0C;&#x8D4B;&#x503C;&#x6210;&#x529F;&#xFF0C;&#x5F53;&#x662F;&#x7B2C;&#x4E8C;&#x6B21;&#x8D4B;&#x503C; <code>next = 5</code>&#x5219;&#x5931;&#x8D25;&#xFF0C;&#x6B64;&#x65F6; <code>get()</code> &#x4E3A;11&#xFF0C;&#x56E0;&#x4E3A;&#x4E0A;&#x6B21;&#x7684; <code>get()</code>&#x4F7F;&#x5F97;&#x5176;&#x81EA;&#x589E;&#x4E86;1.</p>
<h3 id="&#x5C5E;&#x6027;&#x7684;&#x67E5;&#x770B;">&#x5C5E;&#x6027;&#x7684;&#x67E5;&#x770B;</h3>
<p>&#x67E5;&#x770B;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x672C;&#x8EAB;&#x7684;&#x6240;&#x6709;&#x5C5E;&#x6027;&#xFF0C;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;<code>Object.keys</code>&#x65B9;&#x6CD5;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {
  key1: <span class="hljs-number">1</span>,
  key2: <span class="hljs-number">2</span>
};

<span class="hljs-built_in">Object</span>.keys(obj);
<span class="hljs-comment">// [&apos;key1&apos;, &apos;key2&apos;]</span>
</code></pre>
<h3 id="&#x5C5E;&#x6027;&#x7684;&#x5220;&#x9664;">&#x5C5E;&#x6027;&#x7684;&#x5220;&#x9664;</h3>
<p><code>delete</code>&#x547D;&#x4EE4;&#x7528;&#x4E8E;&#x5220;&#x9664;&#x5BF9;&#x8C61;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x5220;&#x9664;&#x6210;&#x529F;&#x540E;&#x8FD4;&#x56DE;<code>true</code>&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = { p: <span class="hljs-number">1</span> };
<span class="hljs-built_in">Object</span>.keys(obj) <span class="hljs-comment">// [&quot;p&quot;]</span>

<span class="hljs-keyword">delete</span> obj.p <span class="hljs-comment">// true</span>
obj.p <span class="hljs-comment">// undefined</span>
<span class="hljs-built_in">Object</span>.keys(obj) <span class="hljs-comment">// []</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>delete</code>&#x547D;&#x4EE4;&#x5220;&#x9664;&#x5BF9;&#x8C61;<code>obj</code>&#x7684;<code>p</code>&#x5C5E;&#x6027;&#x3002;&#x5220;&#x9664;&#x540E;&#xFF0C;&#x518D;&#x8BFB;&#x53D6;<code>p</code>&#x5C5E;&#x6027;&#x5C31;&#x4F1A;&#x8FD4;&#x56DE;<code>undefined</code>&#xFF0C;&#x800C;&#x4E14;<code>Object.keys</code>&#x65B9;&#x6CD5;&#x7684;&#x8FD4;&#x56DE;&#x503C;&#x4E5F;&#x4E0D;&#x518D;&#x5305;&#x62EC;&#x8BE5;&#x5C5E;&#x6027;&#x3002;</p>
<p>&#x6CE8;&#x610F;&#xFF0C;&#x5220;&#x9664;&#x4E00;&#x4E2A;&#x4E0D;&#x5B58;&#x5728;&#x7684;&#x5C5E;&#x6027;&#xFF0C;<code>delete</code>&#x4E0D;&#x62A5;&#x9519;&#xFF0C;&#x800C;&#x4E14;&#x8FD4;&#x56DE;<code>true</code>&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {};
<span class="hljs-keyword">delete</span> obj.p <span class="hljs-comment">// true</span>
</code></pre>
<p>&#x53E6;&#x5916;&#xFF0C;&#x9700;&#x8981;&#x6CE8;&#x610F;&#x7684;&#x662F;&#xFF0C;<code>delete</code>&#x547D;&#x4EE4;&#x53EA;&#x80FD;&#x5220;&#x9664;&#x5BF9;&#x8C61;&#x672C;&#x8EAB;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x65E0;&#x6CD5;&#x5220;&#x9664;&#x7EE7;&#x627F;&#x7684;&#x5C5E;&#x6027;.</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {};
<span class="hljs-keyword">delete</span> obj.toString <span class="hljs-comment">// true</span>
obj.toString <span class="hljs-comment">// function toString() { [native code] }</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;<code>toString</code>&#x662F;&#x5BF9;&#x8C61;<code>obj</code>&#x7EE7;&#x627F;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x867D;&#x7136;<code>delete</code>&#x547D;&#x4EE4;&#x8FD4;&#x56DE;<code>true</code>&#xFF0C;&#x4F46;&#x8BE5;&#x5C5E;&#x6027;&#x5E76;&#x6CA1;&#x6709;&#x88AB;&#x5220;&#x9664;&#xFF0C;&#x4F9D;&#x7136;&#x5B58;&#x5728;&#x3002;&#x8FD9;&#x4E2A;&#x4F8B;&#x5B50;&#x8FD8;&#x8BF4;&#x660E;&#xFF0C;&#x5373;&#x4F7F;<code>delete</code>&#x8FD4;&#x56DE;<code>true</code>&#xFF0C;&#x8BE5;&#x5C5E;&#x6027;&#x4F9D;&#x7136;&#x53EF;&#x80FD;&#x8BFB;&#x53D6;&#x5230;&#x503C;&#x3002;</p>
<h3 id="&#x5224;&#x65AD;&#x5C5E;&#x6027;&#x662F;&#x5426;&#x5B58;&#x5728;">&#x5224;&#x65AD;&#x5C5E;&#x6027;&#x662F;&#x5426;&#x5B58;&#x5728;</h3>
<p><code>in</code>&#x8FD0;&#x7B97;&#x7B26;&#x7528;&#x4E8E;&#x68C0;&#x67E5;&#x5BF9;&#x8C61;&#x662F;&#x5426;&#x5305;&#x542B;&#x67D0;&#x4E2A;&#x5C5E;&#x6027;&#xFF08;&#x6CE8;&#x610F;&#xFF0C;&#x68C0;&#x67E5;&#x7684;&#x662F;&#x952E;&#x540D;&#xFF0C;&#x4E0D;&#x662F;&#x952E;&#x503C;&#xFF09;&#xFF0C;&#x5982;&#x679C;&#x5305;&#x542B;&#x5C31;&#x8FD4;&#x56DE;<code>true</code>&#xFF0C;&#x5426;&#x5219;&#x8FD4;&#x56DE;<code>false</code>&#x3002;&#x5B83;&#x7684;&#x5DE6;&#x8FB9;&#x662F;&#x4E00;&#x4E2A;&#x5B57;&#x7B26;&#x4E32;&#xFF0C;&#x8868;&#x793A;&#x5C5E;&#x6027;&#x540D;&#xFF0C;&#x53F3;&#x8FB9;&#x662F;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = { p: <span class="hljs-number">1</span> };
<span class="hljs-string">&apos;p&apos;</span> <span class="hljs-keyword">in</span> obj <span class="hljs-comment">// true</span>
<span class="hljs-string">&apos;toString&apos;</span> <span class="hljs-keyword">in</span> obj <span class="hljs-comment">// true</span>
</code></pre>
<p><code>in</code>&#x8FD0;&#x7B97;&#x7B26;&#x7684;&#x4E00;&#x4E2A;&#x95EE;&#x9898;&#x662F;&#xFF0C;&#x5B83;&#x4E0D;&#x80FD;&#x8BC6;&#x522B;&#x54EA;&#x4E9B;&#x5C5E;&#x6027;&#x662F;&#x5BF9;&#x8C61;&#x81EA;&#x8EAB;&#x7684;&#xFF0C;&#x54EA;&#x4E9B;&#x5C5E;&#x6027;&#x662F;&#x7EE7;&#x627F;&#x7684;&#x3002;&#x5C31;&#x50CF;&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5BF9;&#x8C61;<code>obj</code>&#x672C;&#x8EAB;&#x5E76;&#x6CA1;&#x6709;<code>toString</code>&#x5C5E;&#x6027;&#xFF0C;&#x4F46;&#x662F;<code>in</code>&#x8FD0;&#x7B97;&#x7B26;&#x4F1A;&#x8FD4;&#x56DE;<code>true</code>&#xFF0C;&#x56E0;&#x4E3A;&#x8FD9;&#x4E2A;&#x5C5E;&#x6027;&#x662F;&#x7EE7;&#x627F;&#x7684;&#x3002;</p>
<p>&#x8FD9;&#x65F6;&#xFF0C;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;&#x5BF9;&#x8C61;&#x7684;<code>hasOwnProperty</code>&#x65B9;&#x6CD5;&#x5224;&#x65AD;&#x4E00;&#x4E0B;&#xFF0C;&#x662F;&#x5426;&#x4E3A;&#x5BF9;&#x8C61;&#x81EA;&#x8EAB;&#x7684;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {};
<span class="hljs-keyword">if</span> (<span class="hljs-string">&apos;toString&apos;</span> <span class="hljs-keyword">in</span> obj) {
  <span class="hljs-built_in">console</span>.log(obj.hasOwnProperty(<span class="hljs-string">&apos;toString&apos;</span>)) <span class="hljs-comment">// false</span>
}
</code></pre>
<h3 id="&#x5C5E;&#x6027;&#x7684;&#x904D;&#x5386;">&#x5C5E;&#x6027;&#x7684;&#x904D;&#x5386;</h3>
<p><code>for...in</code>&#x5FAA;&#x73AF;&#x7528;&#x6765;&#x904D;&#x5386;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x7684;&#x5168;&#x90E8;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {a: <span class="hljs-number">1</span>, b: <span class="hljs-number">2</span>, c: <span class="hljs-number">3</span>};

<span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i <span class="hljs-keyword">in</span> obj) {
  <span class="hljs-built_in">console</span>.log(<span class="hljs-string">&apos;&#x952E;&#x540D;&#xFF1A;&apos;</span>, i);
  <span class="hljs-built_in">console</span>.log(<span class="hljs-string">&apos;&#x952E;&#x503C;&#xFF1A;&apos;</span>, obj[i]);
}
<span class="hljs-comment">// &#x952E;&#x540D;&#xFF1A; a</span>
<span class="hljs-comment">// &#x952E;&#x503C;&#xFF1A; 1</span>
<span class="hljs-comment">// &#x952E;&#x540D;&#xFF1A; b</span>
<span class="hljs-comment">// &#x952E;&#x503C;&#xFF1A; 2</span>
<span class="hljs-comment">// &#x952E;&#x540D;&#xFF1A; c</span>
<span class="hljs-comment">// &#x952E;&#x503C;&#xFF1A; 3</span>
</code></pre>
<p><code>for...in</code>&#x5FAA;&#x73AF;&#x6709;&#x4E24;&#x4E2A;&#x4F7F;&#x7528;&#x6CE8;&#x610F;&#x70B9;&#x3002;</p>
<ul>
<li>&#x5B83;&#x904D;&#x5386;&#x7684;&#x662F;&#x5BF9;&#x8C61;&#x6240;&#x6709;&#x53EF;&#x904D;&#x5386;&#xFF08;enumerable&#xFF09;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x4F1A;&#x8DF3;&#x8FC7;&#x4E0D;&#x53EF;&#x904D;&#x5386;&#x7684;&#x5C5E;&#x6027;&#x3002;</li>
<li>&#x5B83;&#x4E0D;&#x4EC5;&#x904D;&#x5386;&#x5BF9;&#x8C61;&#x81EA;&#x8EAB;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x8FD8;&#x904D;&#x5386;&#x7EE7;&#x627F;&#x7684;&#x5C5E;&#x6027;&#x3002;</li>
</ul>
<p>&#x4E3E;&#x4F8B;&#x6765;&#x8BF4;&#xFF0C;&#x5BF9;&#x8C61;&#x90FD;&#x7EE7;&#x627F;&#x4E86;<code>toString</code>&#x5C5E;&#x6027;&#xFF0C;&#x4F46;&#x662F;<code>for...in</code>&#x5FAA;&#x73AF;&#x4E0D;&#x4F1A;&#x904D;&#x5386;&#x5230;&#x8FD9;&#x4E2A;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {};

<span class="hljs-comment">// toString &#x5C5E;&#x6027;&#x662F;&#x5B58;&#x5728;&#x7684;</span>
obj.toString <span class="hljs-comment">// toString() { [native code] }</span>

<span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> p <span class="hljs-keyword">in</span> obj) {
  <span class="hljs-built_in">console</span>.log(p);
} <span class="hljs-comment">// &#x6CA1;&#x6709;&#x4EFB;&#x4F55;&#x8F93;&#x51FA;</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5BF9;&#x8C61;<code>obj</code>&#x7EE7;&#x627F;&#x4E86;<code>toString</code>&#x5C5E;&#x6027;&#xFF0C;&#x8BE5;&#x5C5E;&#x6027;&#x4E0D;&#x4F1A;&#x88AB;<code>for...in</code>&#x5FAA;&#x73AF;&#x904D;&#x5386;&#x5230;&#xFF0C;&#x56E0;&#x4E3A;&#x5B83;&#x9ED8;&#x8BA4;&#x662F;&#x201C;&#x4E0D;&#x53EF;&#x904D;&#x5386;&#x201D;&#x7684;&#x3002;</p>
<p>&#x5982;&#x679C;&#x7EE7;&#x627F;&#x7684;&#x5C5E;&#x6027;&#x662F;&#x53EF;&#x904D;&#x5386;&#x7684;&#xFF0C;&#x90A3;&#x4E48;&#x5C31;&#x4F1A;&#x88AB;<code>for...in</code>&#x5FAA;&#x73AF;&#x904D;&#x5386;&#x5230;&#x3002;&#x4F46;&#x662F;&#xFF0C;&#x4E00;&#x822C;&#x60C5;&#x51B5;&#x4E0B;&#xFF0C;&#x90FD;&#x662F;&#x53EA;&#x60F3;&#x904D;&#x5386;&#x5BF9;&#x8C61;&#x81EA;&#x8EAB;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x6240;&#x4EE5;&#x4F7F;&#x7528;<code>for...in</code>&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x5E94;&#x8BE5;&#x7ED3;&#x5408;&#x4F7F;&#x7528;<code>hasOwnProperty</code>&#x65B9;&#x6CD5;&#xFF0C;&#x5728;&#x5FAA;&#x73AF;&#x5185;&#x90E8;&#x5224;&#x65AD;&#x4E00;&#x4E0B;&#xFF0C;&#x67D0;&#x4E2A;&#x5C5E;&#x6027;&#x662F;&#x5426;&#x4E3A;&#x5BF9;&#x8C61;&#x81EA;&#x8EAB;&#x7684;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> person = { name: <span class="hljs-string">&apos;&#x8001;&#x5F20;&apos;</span> };

<span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> key <span class="hljs-keyword">in</span> person) {
  <span class="hljs-keyword">if</span> (person.hasOwnProperty(key)) {
    <span class="hljs-built_in">console</span>.log(key);
  }
}
<span class="hljs-comment">// name</span>
</code></pre>
<h2 id="with-&#x8BED;&#x53E5;">with &#x8BED;&#x53E5;</h2>
<p><code>with</code>&#x8BED;&#x53E5;&#x7684;&#x683C;&#x5F0F;&#x5982;&#x4E0B;&#xFF1A;</p>
<pre><code class="lang-js"><span class="hljs-keyword">with</span> (&#x5BF9;&#x8C61;) {
  &#x8BED;&#x53E5;;
}
</code></pre>
<p>&#x5B83;&#x7684;&#x4F5C;&#x7528;&#x662F;&#x64CD;&#x4F5C;&#x540C;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x7684;&#x591A;&#x4E2A;&#x5C5E;&#x6027;&#x65F6;&#xFF0C;&#x63D0;&#x4F9B;&#x4E00;&#x4E9B;&#x4E66;&#x5199;&#x7684;&#x65B9;&#x4FBF;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-comment">// &#x4F8B;&#x4E00;</span>
<span class="hljs-keyword">var</span> obj = {
  p1: <span class="hljs-number">1</span>,
  p2: <span class="hljs-number">2</span>,
};
<span class="hljs-keyword">with</span> (obj) {
  p1 = <span class="hljs-number">4</span>;
  p2 = <span class="hljs-number">5</span>;
}
<span class="hljs-comment">// &#x7B49;&#x540C;&#x4E8E;</span>
obj.p1 = <span class="hljs-number">4</span>;
obj.p2 = <span class="hljs-number">5</span>;
</code></pre>
<p>&#x6CE8;&#x610F;&#xFF0C;&#x5982;&#x679C;<code>with</code>&#x533A;&#x5757;&#x5185;&#x90E8;&#x6709;&#x53D8;&#x91CF;&#x7684;&#x8D4B;&#x503C;&#x64CD;&#x4F5C;&#xFF0C;&#x5FC5;&#x987B;&#x662F;&#x5F53;&#x524D;&#x5BF9;&#x8C61;&#x5DF2;&#x7ECF;&#x5B58;&#x5728;&#x7684;&#x5C5E;&#x6027;&#xFF0C;&#x5426;&#x5219;&#x4F1A;&#x521B;&#x9020;&#x4E00;&#x4E2A;&#x5F53;&#x524D;&#x4F5C;&#x7528;&#x57DF;&#x7684;&#x5168;&#x5C40;&#x53D8;&#x91CF;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">var</span> obj = {};
<span class="hljs-keyword">with</span> (obj) {
  p1 = <span class="hljs-number">4</span>;
  p2 = <span class="hljs-number">5</span>;
}

obj.p1 <span class="hljs-comment">// undefined</span>
p1 <span class="hljs-comment">// 4</span>
</code></pre>
<p>&#x4E0A;&#x9762;&#x4EE3;&#x7801;&#x4E2D;&#xFF0C;&#x5BF9;&#x8C61;<code>obj</code>&#x5E76;&#x6CA1;&#x6709;<code>p1</code>&#x5C5E;&#x6027;&#xFF0C;&#x5BF9;<code>p1</code>&#x8D4B;&#x503C;&#x7B49;&#x4E8E;&#x521B;&#x9020;&#x4E86;&#x4E00;&#x4E2A;&#x5168;&#x5C40;&#x53D8;&#x91CF;<code>p1</code>&#x3002;&#x6B63;&#x786E;&#x7684;&#x5199;&#x6CD5;&#x5E94;&#x8BE5;&#x662F;&#xFF0C;&#x5148;&#x5B9A;&#x4E49;&#x5BF9;&#x8C61;<code>obj</code>&#x7684;&#x5C5E;&#x6027;<code>p1</code>&#xFF0C;&#x7136;&#x540E;&#x5728;<code>with</code>&#x533A;&#x5757;&#x5185;&#x64CD;&#x4F5C;&#x5B83;&#x3002;</p>
<p>&#x8FD9;&#x662F;&#x56E0;&#x4E3A;<code>with</code>&#x533A;&#x5757;&#x6CA1;&#x6709;&#x6539;&#x53D8;&#x4F5C;&#x7528;&#x57DF;&#xFF0C;&#x5B83;&#x7684;&#x5185;&#x90E8;&#x4F9D;&#x7136;&#x662F;&#x5F53;&#x524D;&#x4F5C;&#x7528;&#x57DF;&#x3002;&#x8FD9;&#x9020;&#x6210;&#x4E86;<code>with</code>&#x8BED;&#x53E5;&#x7684;&#x4E00;&#x4E2A;&#x5F88;&#x5927;&#x7684;&#x5F0A;&#x75C5;&#xFF0C;&#x5C31;&#x662F;&#x7ED1;&#x5B9A;&#x5BF9;&#x8C61;&#x4E0D;&#x660E;&#x786E;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">with</span> (obj) {
  <span class="hljs-built_in">console</span>.log(x);
}
</code></pre>
<p>&#x5355;&#x7EAF;&#x4ECE;&#x4E0A;&#x9762;&#x7684;&#x4EE3;&#x7801;&#x5757;&#xFF0C;&#x6839;&#x672C;&#x65E0;&#x6CD5;&#x5224;&#x65AD;<code>x</code>&#x5230;&#x5E95;&#x662F;&#x5168;&#x5C40;&#x53D8;&#x91CF;&#xFF0C;&#x8FD8;&#x662F;&#x5BF9;&#x8C61;<code>obj</code>&#x7684;&#x4E00;&#x4E2A;&#x5C5E;&#x6027;&#x3002;&#x8FD9;&#x975E;&#x5E38;&#x4E0D;&#x5229;&#x4E8E;&#x4EE3;&#x7801;&#x7684;&#x9664;&#x9519;&#x548C;&#x6A21;&#x5757;&#x5316;&#xFF0C;&#x7F16;&#x8BD1;&#x5668;&#x4E5F;&#x65E0;&#x6CD5;&#x5BF9;&#x8FD9;&#x6BB5;&#x4EE3;&#x7801;&#x8FDB;&#x884C;&#x4F18;&#x5316;&#xFF0C;&#x53EA;&#x80FD;&#x7559;&#x5230;&#x8FD0;&#x884C;&#x65F6;&#x5224;&#x65AD;&#xFF0C;&#x8FD9;&#x5C31;&#x62D6;&#x6162;&#x4E86;&#x8FD0;&#x884C;&#x901F;&#x5EA6;&#x3002;&#x56E0;&#x6B64;&#xFF0C;&#x5EFA;&#x8BAE;&#x4E0D;&#x8981;&#x4F7F;&#x7528;<code>with</code>&#x8BED;&#x53E5;.</p>
<h2 id="&#x63A7;&#x5236;&#x5BF9;&#x8C61;&#x72B6;&#x6001;">&#x63A7;&#x5236;&#x5BF9;&#x8C61;&#x72B6;&#x6001;</h2>
<p>&#x6709;&#x65F6;&#x9700;&#x8981;&#x51BB;&#x7ED3;&#x5BF9;&#x8C61;&#x7684;&#x8BFB;&#x5199;&#x72B6;&#x6001;&#xFF0C;&#x9632;&#x6B62;&#x5BF9;&#x8C61;&#x88AB;&#x6539;&#x53D8;&#x3002;JavaScript &#x63D0;&#x4F9B;&#x4E86;&#x4E09;&#x79CD;&#x51BB;&#x7ED3;&#x65B9;&#x6CD5;&#xFF0C;&#x6700;&#x5F31;&#x7684;&#x4E00;&#x79CD;&#x662F;<code>Object.preventExtensions</code>&#xFF0C;&#x5176;&#x6B21;&#x662F;<code>Object.seal</code>&#xFF0C;&#x6700;&#x5F3A;&#x7684;&#x662F;<code>Object.freeze</code>&#x3002;</p>
<ul>
<li><code>preventExtentsions</code></li>
</ul>
<p><code>Object.preventExtensions</code>&#x65B9;&#x6CD5;&#x53EF;&#x4EE5;&#x4F7F;&#x5F97;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x65E0;&#x6CD5;&#x518D;&#x6DFB;&#x52A0;&#x65B0;&#x7684;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-built_in">Object</span>.preventExtensions(object);
object.newValue = <span class="hljs-string">&apos;hello&apos;</span>;

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Test</span>  =<span class="hljs-string">====</span>&gt;</span>
assert.strictEqual(object.newValue, undefined);

<span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Terminal</span>  =<span class="hljs-string">====</span>&gt;</span>
/* &#x901A;&#x8FC7; */
</span></code></pre>
<p>&#x7531;&#x6B64;&#x53EF;&#x4EE5;&#x770B;&#x51FA;&#x6B64;&#x65F6;&#x5BF9;&#x8C61;&#x65E0;&#x6CD5;&#x6DFB;&#x52A0;&#x65B0;&#x5C5E;&#x6027;&#x4E86;&#xFF0C;&#x5373;&#x4F7F;&#x6DFB;&#x52A0;&#x4E86;&#xFF0C;&#x4E5F;&#x83B7;&#x53D6;&#x4E0D;&#x5230;&#x3002;</p>
<p><code>Object.isExtensible()</code>&#x53EF;&#x4EE5;&#x68C0;&#x67E5;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x662F;&#x5426;&#x4F7F;&#x7528;&#x4E86;<code>Object.preventExtensions</code>&#x65B9;&#x6CD5;&#x3002;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#xFF0C;&#x68C0;&#x67E5;&#x662F;&#x5426;&#x53EF;&#x4EE5;&#x4E3A;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x6DFB;&#x52A0;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js">&lt;=====  Test  =====&gt;
assert.strictEqual(<span class="hljs-built_in">Object</span>.isExtensible(object), <span class="hljs-literal">false</span>);

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Terminal</span> =<span class="hljs-string">====</span>&gt;</span>
/* &#x6D4B;&#x8BD5;&#x901A;&#x8FC7;  */
</span></code></pre>
<p>&#x7531;&#x6B64;&#x5982;&#x679C;&#x8FD4;&#x56DE;<code>true</code>,&#x5219;&#x53EF;&#x4EE5;&#x6DFB;&#x52A0;&#x65B0;&#x5C5E;&#x6027;&#xFF0C;&#x5426;&#x5219;&#x4E0D;&#x80FD;&#xFF0C;&#x56E0;&#x4E3A;&#x4E0A;&#x9762;&#x7684;<code>object</code>&#x4E0D;&#x80FD;&#x6DFB;&#x52A0;&#x65B0;&#x5C5E;&#x6027;&#x4E86;&#x6545;&#x800C;&#x8FD4;&#x56DE;<code>false</code>.</p>
<ul>
<li><code>seal</code></li>
</ul>
<p>&#x76F8;&#x5BF9;&#x4E8E;<code>preventExtentsions</code>&#x800C;&#x8A00;&#xFF0C;&#x8BE5;&#x65B9;&#x6CD5;&#x4F7F;&#x5F97;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x65E2;&#x65E0;&#x6CD5;&#x6DFB;&#x52A0;&#x65B0;&#x5C5E;&#x6027;&#xFF0C;&#x4E5F;&#x65E0;&#x6CD5;&#x5220;&#x9664;&#x65E7;&#x5C5E;&#x6027;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">const</span> sealObject = {
  age: <span class="hljs-number">23</span>,
};
<span class="hljs-built_in">Object</span>.seal(sealObject);
<span class="hljs-keyword">delete</span> sealObject.age;

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Test</span>  =<span class="hljs-string">====</span>&gt;</span>
assert.strictEqual(sealObject.age, 23);

<span class="hljs-tag">&lt;<span class="hljs-name">=====</span> <span class="hljs-attr">Terminal</span> =<span class="hljs-string">====</span>&gt;</span>
/**  passing */
</span></code></pre>
<p>&#x7531;&#x6B64;&#x53EF;&#x89C1;&#xFF0C;&#x867D;&#x7136;&#x6211;&#x4EEC;&#x5199;&#x4E86;&#x5220;&#x9664;&#x8BE5;&#x5BF9;&#x8C61;&#x7684;<code>age</code> &#x5C5E;&#x6027;&#xFF0C;&#x4F46;&#x662F;&#x6CA1;&#x6709;&#x8D77;&#x6548;&#x3002;</p>
<p>&#x540C;&#x6837;&#x7684;&#xFF0C;<code>Object.isSealed()</code>&#x65B9;&#x6CD5;&#x80FD;&#x591F;&#x68C0;&#x67E5;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x662F;&#x5426;&#x4F7F;&#x7528;&#x4E86;<code>Object.seal</code>&#x65B9;&#x6CD5;&#x3002;</p>
<pre><code class="lang-js">&lt;=====  Test =====&gt;
assert.strictEqual(<span class="hljs-built_in">Object</span>.isSealed(sealObject), <span class="hljs-literal">true</span>);

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span> <span class="hljs-attr">Terminal</span> =<span class="hljs-string">====</span>&gt;</span>
/* passing */
</span></code></pre>
<p>&#x5982;&#x679C;&#x4F7F;&#x7528;&#x4E86;<code>seal()</code>&#x65B9;&#x6CD5;&#x5219;&#x4E3A; <code>true</code>,&#x5426;&#x5219;&#x4E3A; <code>false</code>&#x3002;</p>
<ul>
<li><code>freeze</code></li>
</ul>
<p><code>Object.freeze()</code>&#x65B9;&#x6CD5;&#x53EF;&#x4EE5;&#x4F7F;&#x5F97;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x65E0;&#x6CD5;&#x6DFB;&#x52A0;&#x65B0;&#x5C5E;&#x6027;&#x3001;&#x65E0;&#x6CD5;&#x5220;&#x9664;&#x65E7;&#x5C5E;&#x6027;&#x3001;&#x4E5F;&#x65E0;&#x6CD5;&#x6539;&#x53D8;&#x5C5E;&#x6027;&#x7684;&#x503C;&#xFF0C;&#x4F7F;&#x5F97;&#x8FD9;&#x4E2A;&#x5BF9;&#x8C61;&#x5B9E;&#x9645;&#x4E0A;&#x53D8;&#x6210;&#x4E86;&#x5E38;&#x91CF;&#x3002;</p>
<pre><code class="lang-js"><span class="hljs-keyword">const</span> freezeObject = {
  age: <span class="hljs-number">23</span>,
};
<span class="hljs-built_in">Object</span>.freeze(freezeObject);
freezeObject.age = <span class="hljs-number">18</span>;

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Test</span>  =<span class="hljs-string">====</span>&gt;</span>
assert.strictEqual(freezeObject.age, 23);

<span class="hljs-tag">&lt;<span class="hljs-name">=====</span> <span class="hljs-attr">Terminal</span> =<span class="hljs-string">====</span>&gt;</span>
/* passing */
</span></code></pre>
<p>&#x7531;&#x6B64;&#x53EF;&#x89C1;&#xFF0C;&#x867D;&#x7136;&#x6211;&#x4EEC;&#x6539;&#x53D8;&#x4E86;&#x5BF9;&#x8C61;&#x7684;<code>age</code>&#x5C5E;&#x6027;&#xFF0C;&#x4F46;&#x662F;&#x5B9E;&#x9645;&#x4E0A;&#x5E76;&#x6CA1;&#x6709;&#x4FEE;&#x6210;&#x529F;&#xFF0C;&#x503C;&#x4F9D;&#x7136;&#x6CA1;&#x6709;&#x53D8;&#x5316;&#x3002;</p>
<p>&#x540C;&#x6837;&#x7684;&#xFF0C;<code>Object.isFrozen()</code>&#x65B9;&#x6CD5;&#x7528;&#x4E8E;&#x68C0;&#x67E5;&#x4E00;&#x4E2A;&#x5BF9;&#x8C61;&#x662F;&#x5426;&#x4F7F;&#x7528;&#x4E86;<code>Object.freeze()</code>&#x65B9;&#x6CD5;&#x3002;</p>
<pre><code class="lang-js">&lt;=====  Test  =====&gt;
assert.strictEqual(<span class="hljs-built_in">Object</span>.isFrozen(freezeObject), <span class="hljs-literal">true</span>);

<span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">=====</span>  <span class="hljs-attr">Terminal</span>  =<span class="hljs-string">====</span>&gt;</span>
/* passing */
</span></code></pre>
<p>&#x5982;&#x679C;&#x4F7F;&#x7528;&#x4E86;<code>freeze()</code>&#x65B9;&#x6CD5;&#xFF0C;&#x5219;&#x8FD4;&#x56DE;<code>true</code>,&#x5426;&#x5219;&#x8FD4;&#x56DE;<code>false</code>.</p>
<h4 id="&#x5C40;&#x9650;&#x6027;">&#x5C40;&#x9650;&#x6027;</h4>
<ul>
<li><p>&#x4E0A;&#x9762;&#x7684;&#x4E09;&#x4E2A;&#x65B9;&#x6CD5;&#x9501;&#x5B9A;&#x5BF9;&#x8C61;&#x7684;&#x53EF;&#x5199;&#x6027;&#x6709;&#x4E00;&#x4E2A;&#x6F0F;&#x6D1E;&#xFF1A;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x6539;&#x53D8;&#x539F;&#x578B;&#x5BF9;&#x8C61;&#xFF0C;&#x6765;&#x4E3A;&#x5BF9;&#x8C61;&#x589E;&#x52A0;&#x5C5E;&#x6027;&#x3002;</p>
</li>
<li><p>&#x5982;&#x679C;&#x5C5E;&#x6027;&#x503C;&#x662F;&#x5BF9;&#x8C61;&#xFF0C;&#x4E0A;&#x9762;&#x8FD9;&#x4E9B;&#x65B9;&#x6CD5;&#x53EA;&#x80FD;&#x51BB;&#x7ED3;&#x5C5E;&#x6027;&#x6307;&#x5411;&#x7684;&#x5BF9;&#x8C61;&#xFF0C;&#x800C;&#x4E0D;&#x80FD;&#x51BB;&#x7ED3;&#x5BF9;&#x8C61;&#x672C;&#x8EAB;&#x7684;&#x5185;&#x5BB9;&#x3002;</p>
</li>
</ul>

                                
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